Method of making motor-compressor units for refrigeration



a v I f Aug. 25, 1942. KUCHER 2,294,037

METHOD OF MAKING A MOTOR-COMPRESSOR UNIT FOR REFRIGERATION OriginalFiled' April 30, 1937 4 Sheets-Sheet l I VEN OR.

ATTORNEYS.

9 A. A. KUCHER 2,294,037

METHOD OF MAKING A MOTOR-COMPRESSOR UNIT FOR REFRIGERATION OriginalFiled April 30, 1937. 4 Sheets-Sheet 2 INVENTOR. Muwfi,MW

ATTORNEYS.

Aug. 1942. uc 2,294,037

METHOD OF MAKING MOTOR-COMPRESSOR UNIT FOR REFRIGERATION Original FiledApril 50, 1937 4 Sheets-Sheet 3 r IEVENEQR. BY Mm P912462) ATTORNEYSAug. 25, 1942. A. A. KUCHER 2,294,037

METHOD OF MAKING A MOTOR-COMPRESSOR UNIT FOR REFRIGERATION 'Ori-ginalFiled April 30, 1937 4 Sheets-Sheet 4 INVENTOR Mai/94W BY 1 z 795'.

ATTORNEYS.

Patented Aug. 25, 1942 METHOD OF MAKING MOTOR-COMPRESSOR UNITS FORREFRIGERATION Andrew A. Kucher, Dayton, Ohio, assignor to General MotorsCorporation, Dayton, Ohitna corporation of Delaware Original applicationApril 30, 1937, Serial No.

139,989. Divided and this application June 28, 1939, Serial No. 281,668

2 Claims. (oi. 29-1564) This invention relates to refrigeration and moreparticularly to a motor-compressor unit for use in refrigerating systemsand the manufacture thereof.

This application is a division of my copending application Serial No.139,989 filed April 30, 1937/ Patent No. 2,243,464, which is a divisionof Pat ent No. 2,130,349.

It is among the objects of this invention to provide a motor-compressorunit which may be made very accurately, and is capable of operating athigh emciencies notwithstanding the fact that the parts are easily madefor quantity production and may be assembled without troublesomeselectivity.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a view, partly in vertical cross-section and partlydiagrammatic of a refrigerating system including the motor-compressorunit;

Fig. 2 is a horizontal cross-sectional view taken along the line 2-2 ofFig. 1;

Fig. 3 is a vertical cross-sectional view taken along the line 3--3 ofFig. 1;

Fig. 4 is a bottom view of the unit shown in Fig. 1;

Fig. 5 is an exploded view of the unit, particularly useful in showingthe various steps of as-- sembly of the unit;

Figs. 6 to 13 inclusive illustrate the various steps which may beperformed by standard machine tools in the manufacture of the compressorunit;

Fig. 14 is a cross-sectional view of a portion of the mechanism shown inFig. 2 with a slightly modified form of divider;

Fig. 15 is a cross-sectional view somewhat similar to Fig. l, but withthe driv shaft shown in elevation;

Fig. 16 is a cross-sectional view looking down on the top of thecompressor. This figure indicates by the line I! the cross-section alongwhich Fig. 1 is taken; and

Fig. 17 is a cross-sectional view taken along the line ll|l of Fig. 16.

According to this invention it is possible to produce a motor-compressorunit in which substantially all of the parts can be accurately andcheaply made and which the assembly may be performed speedily andwithout the necessity of careful fitting, lapping or the like.Notwithsurfaces with each other.

standing this ease of manufacture, a unit made in accordance with thisinvention is of extremely high efiiciency and is capable of operating atexceptionally low current consumption and high refrigerating efficiency.

While this unit is particularly adapted to manufacture by the use of thesimplest of machine-=- shop tooling operations, it is to be understoodthat many of the features and advantages of this invention may beutilized where a more specialized tool equipment is desired either bypreference or because of prior acquisition.

In the manufacture of this motor-compressor unit, advantage is taken ofthe extreme accuracy of certain types of standard or special tools, whenthey aie limited to producing cylindrical surfaces about a common axisor of a predetermined eccentricity and also when they are limited toproducing plane surfaces at right angles to the axes of the cylindricalsurfaces, The moving parts of the unit, which must maintain closetolerances in order to operate freely and to maintain fluid seals duringthe compressing operation, may be finished by standard grinding toolswhich produce accurately cylindrical surfaces about any desired axis andplane surfaces at right angles to such axis.

The motor-compressor unit is manufactured preferably by forming a cupmember with certain parts of the unit assembled therein and by forming asealing member with other parts of the unit assembled thereon andthereafter assembling .these two members by telescoping cylindricalsurfaces with each other and by abutting plane The entire assembly isguided by a stationary shaft which is rigid with respect to one of themembers and slides into a slot or cylindrical receiving surface inthe-other member, the working parts of the unit thus being broughttogether easily with the least likelihood of distortion or binding andwith extreme accuracy.

The cup member, above referred to, preferably has the motor statorassembled therein. The

and the compressor are drivingly connected by means of a drive shaft,sleeve or eccentric H, these parts being all produced with cylindricalcooperating surfaces in a manner more fully to be described.

Some of the preferred steps in the production of the cup member areshown at Fig. 6. The shell of the member in is first roughly produced bya drawing operation from deep drawing steel. This operation iswell-known and need not be specifically illustrated. This drawingoperation produces the general outline of the shell ID, with asubstantial-thickness of material throughout the shell. The shell thusroughly formed is placed in a fixture 20 held on the rotating spindle 2|of a standard grinding machine, and several cylindrical surfaces,preferably internal, are produced therein by an internal grindingmachine or a lathe, whose rotary grinding memher or cutting tool isdiagrammatically shown at 22, and by a reaming device 23. One or moreplane surfaces also are produced by face grinding, while the cup memberill is held in the fixture, to insure that all cylindrical surfaces aretruly coaxial to the common axis of the member ID and that the planesurfaces are at a true right angle to the said common axis. Thus theinternal cylindrical surface 24 is produced for the reception of thestator H. The internal cylindrical surface 25 is produced, so that thestator may be inserted in the member Ill without undue resistance. Aninternal cylindrical surfac 26 is produced for the reception of thesealing member '2 in a manner hereafter to be more fully described. Alsoan internal cylindrical shaft receiving surface 21 is produced,preferably by the reaming device 23. These surfaces 24 to 26 inclusiveare truly coaxial because cup member I is maintained in the fixture 20and rotates with the spindle 2|. In addition, one or more plane surfacesare produced on the member 50. Thus the plane surface 28 is produced asa stop for the stator ii, the plane abutting surface 29 is produced forreceiving the corresponding abutting surface on the sealing member i2hereafter to be described. The surface 30 need not be a true planesurface, but conveniently can remain as formed by the internal grindingtubes.

The motor stator i I is forced into the cylindrical surface 24 of themember if] by any standard press. The stator Ii preferably is formedwith an external cylindrical surface 3i and an internal cylindricalsurface 32, these surfaces being rendered substantially coaxial duringthe manufacture of the stator so that when a stator is forced into thesurface 29, the internal cylindrical surface 32' of the stator will besubstantially coaxial with the common axis of the member iii withintolerances required for proper cooperation with the motor rotor.

The sealing member I2 preferably is made of deep drawing steel and isstamped roughly to the shape shown in Fig. '7. This member has weldedthereto a stamped plate 33 and a stationary shaft IS, the plate 33 andthe shaft l3 being welded so that they are substantially integral withthe sealing member l2. The plate 33 has an annular groove 33a adjacentthe shaft [3 for the recep tion of a thrust washer 33b hereafter to bemore fully described. After the welding operation, the sealing member iscentered on the members 34 and 35 of a cylindrical grinding machine andfixed to be rotated by pin 36 on the machinetool member 34 whichcooperates with the recess 31 to be more fully hereafter described. Bycylindrical grinding operations, an external cylindrical telescopingsurface is produced by the cylindrical grinding tool 39 which alsoproduces one or more external cylindrical bearing surfaces to and 4! andthe grinding surface 42 on the shaft 53. The cylindrical surfaces 33,40, 4| and 42 are truly coaxial since they are produced by externalcylindrical grinding members about a common axis without disturbing theset-up. In addition, the plane abutting surface 43 and the planecompressor receiving surface 44 are produced by face grinding operationsindicated at 85 and 46. Since these are also produced on the same setup,they are truly at right angles to the common axis of the sealing member.

The drive shaftll is also finished by grinding operationsdiagrammatically shown in Fig. 8.

- The rough blank of the drive shaft is formed with an internalcylindrical bearing surface 41 preferably by a reaming operation (notshown) and thereafter is mounted on a mandrel 48 which cooperates withthe internal cylindrical bearing surface. The drive shaft fits snugly onthe mandrel. The motor rotor receiving surface 49 is roughly straightknurled in any suitable manner, or may be made tapered in order toeffect a driving fit between the motor rotor l4 and the surface 49. Thesurface 49 need not be finished to relatively close limits sinceultimately it is necessary only to maintain the rotor-stator gap. Themandrel 48 is eccentrically mounted on the centers 50 and 5| and isdriven by the dog 52 and by the chuck at 5i. External eccentriccylindrical surfaces 53 and 54 are ground on the drive shaft by means ofexternal cylindrical grinding member 55. The motor rotor I5 is producedwith an internal cylindrical surface 56 and an external cylindricalsurface 51, so that the same may be forced on the drive shaft by anystandard press operation and so that the external cylindrical surface 51is substantially coaxial with the internal cylindrical surface 41 withinthe tolerance required for proper cooperation with the motor stator II.However, if the surface 49 has been made tapered or conical, theinternal surface 56 of the rotor is also made conical to cooperatetherewith. It is to be understood, however, that the motor stator l4 maybe assembled on the drive shaft and its external surface 51 may beground by placing the mandrel on the center position in a lathe, so thatthe surface 5? may be made truly coaxial with the internal surface 41.

The compressor is preferably formed of a stationary pumping cylinder l5and a rotary piston I 6. The pumping cylinder I5 preferably is formed asshown in Figs. 9 to 12 inclusive. The rough blank, which may be aroughly formed annulus, has a slot Bil formed therein and tinished toaccurate dimension by the face grinding tool 6! while held in the viseor fixture 62. Preferably the slot 60 is formed parallel with the radiusof the annulus. The notches are also cut adjacent the slot 60.Thereafter a motor spacing block 63, which has been made very carefullyto size, is placed in the slot 60 and a clamp 64 is placed in thenotches 65. The clamp B l-brings the two sides of the slot 60 closelyagainst the block 63 and spaces them exactly for the reception of thedivider 65 hereafter to be more fully described. After the block 63 isfirmly in place, the annulus is placed in a chuck 61 which is held onthe rotary spindle 68. While in this position, an internal cylindricalsurface 69 is formed by an internal rotary grinding tool I0, and one endplane surface H is face cut by the radial grinding tool12. Since thesetwo surfaces are ground while the annulus is in the chuck 61, thesurfaces 69 and II are truly at right angles to each other. The annulusis then placed on a magnetic chuck "I3 and the other end plane surfaceI6 is produced by the surface grinding tool I5. This is a standardgrinding machine which insures a truly parallel rela- 6?, but of smallersize to accommodate the pis-' ton I6 and an internal cylindrical surface16 is cut by an internal grinding operation similar to that produced bythe tool I on the surface 69. Also one end plane surfacel'l is cut by aface grindin tool similar to the tool I2, producing the surface ll trulyat right angles, internal cylindrical surface it. Thereafter the annulusis assembled tightly on the mandrel 'lfi and an external cylindricalsurface 19 is ground by placing the mandrel 18 on the center members-80and Bi and by producing a cylindrical grinding action by the tool 82.This operation insures that the surfaces It and 19 are truly coaxial.Thereafter the annulus I6 is placed on the magnetic chuck similar, tothe chuck I3 with the surface ll adjacent the chuck-and the end planesurface 83 is ground by surface grinding tool similar to the tool "I5 toinsure that the plane surfaces TE and 83 are truly parallel with eachother and at right angles to the axis of the piston I0.

Proper bolt holes, threaded and plain, are produced on the partswherever necessary. The bolts need not have a tight fit on the plainholes, because the parts are held in place by the longitudinal clampingaction of the bolts.

The foregoin operations described with respect to Figs. 6 to 13inclusive, may be produced on standard tools, utilizing carefully mademandrels or blanks, and as will be understood by one skilled in the art,such procedure may be made to insure coaxiality and perpendicularitywithin any reasonable tolerance desired, so that the parts so producedwill have cylindrical surfaces coaxial with each other, or eccentricwith each other to any degree of eccentricity desired and with planesurfaces at rightangles to the cylindrical surfaces within any degree ofperpendicularity desired. While these parts may be made on standardmachine-shop tools, it is to be understood that special tools may beused to produce the parts, if so desired.

.A thrust bearing is provided to support the weight of the drive shaftI1 and the rotor It. This may be provided by forming an annular channelin the plate 33 adjacent the shaft I3 for the reception of a hard steelsplit ring 331) which extends slightly above the surface of the plate33. Preferably the shaft l3 has acavity I28 of smaller diameter than itsbearing surface adjacent the groove for the ring 33b. This permits thegrinding tools to finish the surfaces on the plate 33 and the shaft I3without necessity of care at the intersecting corner of the surfaces.

The parts above described are assembled on the sealing member I I asfollows. A guiding mandrel 85, (Fig. 5) which has been very carefullymade with internal and external cylindrical surfaces properly coaxialand of the proper diameters, and with a bottom plane surface at trueright angles to its cylindrical surfaces, is placed over the stationaryshaft I3. The internal cylindrical surface of the mandrel fits closelyon the bearing surface 40 of the shaft and is of such a size that it isa proper guide for the stationary pumping cylinder I5. The pumpingcylinder I5 with the block 63 and clamp 60 still in place is telescopedover the mandrel 85 and is securely fastened to the plate 33 by means ofthe bolts 86. These bolts are of sufilcient power, so that when theclamp M is released, they firmly hold the stationary cylinder It withexactly the same spacing in the slot 60 which prevailed when the clampwas in place. Thereafter the mandrel 85 is manually removed by means ofthe knurled surface 8'? which extends above cylinder I5 when thecylinder is in place. The rotary piston I6 is placed within thestationary cylinder l5 and the top cover plate 88 of the compressor isclamped to the cylinder It by means of screws 89. The top plate 88 isformed with the'bottom surface 90 as a true plane surface and thecylinder I5 and piston 56 are made substantially of the same length butwith the cylinder If: just slightly longer (about .0004 inch extralength in a small household model), so that when the plate 90 is inplace, the end surfaces ii and 83 will have a sealing relation withrespect to the surfaces at and 90 because of the oil film produced ashereinafter more fully described. After the plate. 88 is in place, theoil cup member at is secured by means of screws 92 to the plate 88 withthe gasket Qla between. The split thrust washer 33b which has a radiallydisposed oil passage 330 is then placed in the groove 33a with the uppersurface above plate 33. The drive shaft It, with its assembled motorrotor It is telescoped over the stationary shaft I3 into the piston 55,to rest on the thrust washer 33b, the piston It being moved to theproper position to receive the eccentric surfaces 53 and 5d of the shaftI'l. Thereafter the cup member I0 and the sealing member l2 areassembled by telescoping the cylindrical surfaces 2'6 and 30, byabutting the plane surfaces 29 and 03 and by telescoping the end 93 ofthe shaft I3 in the cylindrical surface 2'! of the member 50. When thesemembers have been driven in place, the end 90 of the cup member iscurled around the flange 95 of the sealing member l2 and is soldered orbrazed as shown at 06.

Other features may be embodied in the motorcompressor unit to enhanceits emciency without impairing the ease of manufacture. Thus thestationary shaft I3 may be made hollow and may extend through thesealing member I2. This hollow shaft may have a radial opening I00 toreceive the compressed refrigerant which then flows through thelongitudinal passage IOI of the shaft l3 and is discharged into the pipeI02 connected to the end of the shaft I3. From thence the refrigerantflows to the condenser I03, and, in a liquefied form, flows through thepipe I04 to the heat interchanger I05 and from thence to the expanderI06, then through the evaporator I01 and through the interchanger I05and pipe I08 to the inlet fixture 31. The inlet fixture 31 may be in theform of a nipple which passes through the sealing member I! and is heldin place by the plate 33 when it is welded. The nipple may also includea screen I09, the plate 33 being provided with a passage IIO leading tothe space between the cylinder I5 and the rotary piston l6.

The cylinder I5 is provided with a divider or follower 66 ofsubstantially the same length as the piston I6. This divider is providedwith one or more cylindrical pins I I I around which are placed springsI I2 which bear radially outwardly against the inverted oil cup portionII3 of the oil cup member 9|. If desired, the divider is provided with ahalf moon member I M to increase the sealing surface adjacent to therotary piston I6 as shown in Fig. 2, or the end may be made flat, beingtangential to the piston, as shown in Fig. 14.

Oil is placed In the unit to the level H5, and, since the oil is undercompression pressure, and leaks slowly along the follower 66, the oilwill be forced up into the inverted cup-shaped member H3 and thuslubricate the entire vertical extent of the spacer or follower 66.

Lubrication for the internal portion of the compressor and for thebearing or bearings on the stationary shaft I3 are provided. For thispurpose the oil cup member 9i is provided with an the annular valve seatI24. The compressed re- 1 frigerant, together with the oil which isforced past the divider 56 is discharged up through the passageway I22and past the valve I23, comprising a metal reed secured by the screwsI23a to the plate 38, into the cup compartment I20. tends to fill thecompartment with a substantial quantity of oil which thus submerges theopening I25 in the plate 88 in oil. A certain part of the oil from thecompartment I20 forms a secondary lubricating cycle by flowing radiallyoutward between the pston I6 and the plates 88 and 33 to be againdischarged through the discharge opening I22 into the compartment I20.Another part of the oil from compartment H0 is forced upwardly betweenthe stationary shaft I3 and the drive shaft IT to lubricate theircooperating hearing surfaces. To this end, the oil flows down betweenthe eccentric surfaces 53 and 5 3 and the internal cylindrical surfaceI5 of the piston I6, providing proper lubrication at this point, and isgiven a force-feed action by the groove I26 cut in the eccentricsurfaces 53 and 54. This forces the oil down to the bottom of the driveshaft, where 'a portion flows outwardly between the piston I6 and theplate 33, while another portion lubricates the lower end of the driveshaft I1 and flows through the passage 33a in the thrust washer 33bradially inwardly into the space between the drive shaft I1 and thestationary shaft I3. The oil then fills the cavity I28 and is forced upthrough the spiral groove I29 in a force-feed manner by th'e'rotation ofthe shaft, so that the oil flows through the cavity I30 to the upperbearing surface I3I between the stationary shaft and the drive shaft.Some of the oil passing through this latter bearing is dischargedradially along the rotor and flows back to the oil space in the bottomof the compressor unit. The refrigerant discharged into the cup memberI20 flows through the annular opening I32 and thence through openingsI33 in the rotor It to the space above the rotor, so that the gas andoil are given separating action while flowing through the openings I33.The gas passes to the openings I00 and the oil flows radially out- This' ward and back through the rotor stator space. by

gravity to the bottom of the compressor unit. Suitable electricallead-ins I 34 are provided in the sealing member I2, for connecting thestator with the source of power. A suitable plug I35 is provided forfilling or draining the unit.

If desired the outside of the casing may be provided with fins I36brazed or soldered to the casing to radiate a portion of the heat of theunit. These fins may be formed of a single piece of metal bent in azig-zag manner as shown in Fig. 4.

The outer surfaces of the shaft and the upper surface of the plate I0may be given a hard finish preferably by a chrome plate finish. Thisfinish may be applied electro-chemically. To this end the grindingoperations on the steel may be carried out by giving allowance forsubsequent plating, after which careful chrome plating may be performedwith subsequent burnishing of the finish.

The motor rotor may be provided with counterbalance I10 and MI. Thecombined moments of the counter-balance Ill and of the rotary parts of ithe compressor are made equal to the moment of the counter-balance I10,thus providing a dynamic balance in the unit.

' The length of the surface 26 and of the flange 38 are such that thecurled portion I'I2 may be ground off and the unit disassembled three ormore times. When the unit is reassembled, the length of the flange 38 isreduced sufiiciently to permit another portion of the surface 26 to becurled around the end.

Preferably adjacent parts of the unit which bear against each other aremade of different hardness. Thus the plate 33 and the shaft I3 are madeof soft steel with their bearing surfaces chromium plated as describedabove. The rotary piston I6 is made of soft steel and is glass hardened.The shaft I1 is soft steel, hardened slightly less than the piston I6,but the outside surface may alternately be chromium plated. The cylinderI5 is soft steel, heat treated by alternate heating and cooling, torelieve internal stresses. The follower 66 is made of soft steel, glasshardened slightly less than piston IS. The cover plate is made of softsteel, heat treated similarly to cylinder I5. The cup member I0 and thesealing member I2 are made of a stamp stock, preferably of soft drawingsteel.

This motor-compressor unit is particularly adapted for use inrefrigerating where the compressor unit operates continuously asdescribed in my copending application Serial No. 599,239. It is alsoparticularly adapted for use with a refrigerant and lubricant ,which arecompletely miscible in each other whether the compressor operatescontinuously or not. It also may be used for intermittent operation orwith refrigerants and lubricants which are not completely miscible ineach other.

This motor-compressor unit is particularly adapted to be made withoutthe use of cast metal.

While the form of embodiment of the invention as herein d'sclosed,constitutes a preferred form,

it is to be understood that other forms might be clamping a block in theslot of a slotted rotary compressor cylinder, positioning the cylinderon said end wall, securing the cylinder in place on the end wall andthereafter removing the block.

2. The method of assembling a slotted rotary compressor cylinder, an endwall for said cylinder and a slidable divider block which comprises,placing a temporary spacing block in the slot,

clamping the temporary spacing block in place so as to maintain thedimensions of the slot opening correct, positioning the.cylinder on theend wall, fixedly securing the cylinder in place on the end wall whilethe temporary block is in place and then removing the block andreplacing the temporary spacing blockwith a slidable divider block.

ANDREW A. KUCHER.

